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Green Means Caution, White Means Go?

July 16, 2015

Written byCuriosity Staff

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Although it is universally understood by drivers of all ages these days, green didn't always mean "go" for traffic lights on the road. The first traffic signals used the color red to mean "stop," green meant "caution," and white meant "go." This system of color changed after an accident occurred: A red lens fell out, so the red light appeared white, which meant "go." The green and red color scheme comes directly from railroad signals.